Natural Sorbents Research Articles

Effect of glauconite-containing wastes obtained during phosphorite enrichment on lead mobility in soils

Lead (plumbum, Pb) is a toxic element of the first hazard class. Global soil pollution with Pb leads to severe consequences for the environment and human health. Mobile Pb forms represent a special environmental danger. To immobilize Pb in soils, various materials (meliorants) are used which can convert it into some form poorly soluble in water and weak acids. The search for safe natural materials for the rehabilitation of contaminated soils is of great practical importance. Glauconite-containing phosphorite tailings (PT) are promising reclamation materials. The main component of PT, glauconite, is a natural sorbent capable of binding heavy metals. The composition of PT also includes small-fraction phosphorites, clay and calcareous components, and quartz. The effect of PT on lead mobility in soil was studied in laboratory conditions. Four variants of loamy soil with various chemical structures were used. The lead content in different soil samples did not differ statistically significantly from each other. The effect of PT on lead mobility was evaluated in comparison with limestone. The meliorants were introduced in a dosage of 1 g / kg. The use of PT led to active Pb immobilization in acidic organic–depleted soils, while lime did so in neutral highly humus soils. Mathematical processing of our experimental results suggests that the formation of sedentary complexes with organic matter and adsorption of lead on glauconite serves the predominant mechanism of binding Pb in soil when using lime and PT, respectively. The introduction of PT causes a decrease in the Pb mobility, as well as the enrichment of the soil with phosphorus, potassium, sulfur, calcium and trace elements contained in this meliorant. This is important for restoring the fertility of degraded lands.

Cobalt Biosorption in Fixed-Bed Column Using Greenhouse Crop Residue as Natural Sorbent

Intensive greenhouse agriculture annually produces large amounts of residues. The present work focused on the study of the dynamic adsorption of cobalt from aqueous solutions over a vegetal residue from intensive greenhouse cultivation. The influence of three operating variables, feed-flow rate, inlet concentration of cobalt and bed height, was analyzed. According to the results, the variable that particularly affected the percentage of cobalt adsorbed was the feed-flow rate. The results were also fitted to an adaptive neuro fuzzy system (ANFIS) model to predict cobalt adsorption from aqueous solutions and choose the most favorable operating conditions. Results were evaluated using root mean squared error (RMSE), coefficient of determination (R2) and other typical statistic factors as performance parameters. The experimental and model outputs displayed acceptable result for ANFIS, providing R2 values higher than 0.999 for both cobalt removal (%) and biosorption capacity (mg/g). In addition, the results showed that the best operating conditions to maximize the removal of cobalt were 4 mL/min of feed-flow rate, 25 mg/L of inlet concentration and 11.5 cm of bed-height.

Adsorption study of oil spill cleanup from sea water using natural sorbent

Lawsonia leaves were used as biodegradable biomass in the oil spill cleanup from seawater. Spilled oil mass, removal time, adsorbent dose, and sorption temperature are the main parameters studied in the oil/water system. At room temperature (28 °C), the optimum oil capacity reached 1.60 g/g at 2 min. Sorption system was modeled by isotherm (Freundlich, Langmuir, Redlich-Peterson) and kinetic (Pseudo-first-order, Pseudo-second-order, Elovich, and Intraparticle) models. Langmuir isotherm appeared best-fitting models with R2: 0.9541 indicating oil sorption monolayer onto Lawsonia leaves. In addition, the results are good fitting with the Pseudo-first-order kinetic model (R2: 0.9732) compared to other models representing the physical sorption of oil onto Lawsonia leaves and the sorption thermodynamic appeared an exothermic sorption system. Furthermore, the reusability of Lawsonia leaves established the economic recycled of biomass up to 4 sorption cycles.

Experimental study of the sorption properties of natural zeolite-containing tripolite and their ability to purify aqueous solutions contaminated with Ni and Zn.

Sorption properties of natural zeolite-containing tripolite from the Khotynetsky deposit (Russia, Oryol region) were studied to evaluate their possibility to purify ground waters contaminated by technogenic Ni2+ and Zn2+. According to experimental data the total ion-exchange capacity of the natural tripolite sample equaled to 1.79mg-eq/g. The kinetic experiments showed that equilibrium in the studied rock-solution system took place after 500h of interaction. In the range of the used Ni2+ and Zn2+ concentrations (2-10mg/L) after 21days of interaction with natural tropolite suspension, the sorption of the studied ions can be approximated by a linear isotherm, zinc being sorbed much better than nickel: the average values of distribution coefficients (Kd) obtained for 0.003N CaCl2 aquatic solution equaled to 2.7 × 103ml/g for Ni2+ and 6.7 × 103ml/g for Zn2+. Therefore, natural zeolite-containing tripolite of the Khotinetsky deposit can be used for extraction of technogenic Ni2+ and Zn2+ from natural surface and ground waters contaminated by these ions and can be considered as an effective natural sorbent for solving environmental problems.

Substrates based on composted sewage sludge for land recultivation

Increasing a large amounts of sewage sludge in Ukraine is an urgent environmental problem that requires the selection of an effective strategy for their disposal. The usage of sludge composting technology leads to the restoration of sludge as a resource and is cost-effective and environmentally sustainable compared to the method of landfilling. The purpose of this research is to carry out bioindication tests of growth substrates based on composted sewage sludge with the subsequent possibility of their usage in the technology of recultivation of landfills for municipal solid waste. The experiment was performed on four types of compost with different modifications of the natural sorbent - zeolite. During the experiment the average percentage of germination of polygamous ryegrass plants (Lolium perenne L.) was determined in the investigated substrates. The mass and length of the aboveground part of the plant and roots were also measured. The results showed that the addition of natural sorbent to substrates has a positive effect on growth and development of plants. This investigation was conducted in accordance with the current norms of national standards of Ukraine: DSTU 7369 (2013), "Wastewater. Requirements for wastewater and its sediments for irrigation and fertilization"; DSTU ISO 11269-1 (2004), "Soil quality. Determination of the effect of pollutants on soil flora. Part 1: Method for determining the inhibitory effect on a root growth"; DSTU ISO 11269-2 (2002), "Soil quality. Determination of the effect of pollutants on soil flora. Part 2: Effects of Chemicals on Germination and Growth of Higher Plants". The experiment was conducted on four types of compost with different modifications of the natural sorbent - zeolite in percentage amounts: 0; 2.5; 5; 7.5, dark-grey gilded soil was used as a control element. In the experiment, the average percentage of germination of polygamous ryegrass plants (Lolium perenne L.) on the studied substrates was determined. The mass and length of the aboveground part of the plant and roots were also measured. The first sprouts of ryegrass began to appear on the 7th day of the experiment. The highest average value on the seventh day of germination was 90% in the control sample with 5% of sorbent content and in K2 substrate in the sample with 7.5% sorbent content. However, the germination of plants in substrates K3 and K4 occurred later compared with substrates K1, K2, and control. For substrate K1 in the sample with a sorbent content of 5%, plant germination was the highest and was 100%. The highest average value of ryegrass stem length is observed in variant K4 in the sample with 0% zeolite content and in variant K1 in the sample without zeolite content the lowest average value of stem length was observed. The K3 and K4 variants have a more developed root system compared to other variants. Based on the obtained data it can be assumed that the most optimal universal component for creating a growth substrate is variant K3 (mixture of "newly picked" and "old" SS) which has not so developed aboveground part but has very branched root system that allows to adapt to various environmental factors and in combination with a small proportion of natural sorbents can be effective for the recultivation of MSW landfills, which in its turn minimizes the need to use a fertile soil layer.

Use of natural sorbents for accelerated bioremediation of grey forest soil contaminated with crude oil

Due to the extensive oil extraction and transportation that occurs in oil-producing countries, many lands remain contaminated because of accidental leakages. Despite its low cost and environmentally safe nature, bioremediation technology is not always successful, mainly because of the soil toxicity to the degrading microbial populations and plants. Here we report a three-year microfield experiment on the influence of natural sorbents of mineral (zeolite, kaolinite, vermiculite, diatomite), organic (peat), carbonaceous (biochar) origin, and a mixed sorbent ACD (composed of granular activated carbon and diatomite) on the bioremediation of grey forest soil contaminated with weathered crude oil (40.1 g total petroleum hydrocarbons (TPH) kg−1). Optimal doses of the sorbents significantly accelerated bioremediation of petroleum-contaminated soil through bioaugmentation followed by phytoremediation. The main reason for the influence of the sorbent amendments relied upon the creation of optimal conditions for the activation of hydrocarbon-utilizing bacteria and plant growth due to the reduction of soil toxicity, as well as maintaining an optimal pH and water-air regime in the soil. That happened because of reducing the soil hydrophobicity, increasing porosity and water holding capacity. The content of the TPH in the best samples (2% biochar or ACD) reduced to their local permissible concentration accepted for remediated soils in the Russian Federation (≤5 g kg−1) after two warm seasons compared to that after three warm seasons in the other samples. Although some sorbents decelerated biodegradation of highly condensed polycyclic aromatic hydrocarbons (PAHs, including benzo(a)pyrene) in the soil, the overall risk from the residual contaminants present in the remediated soil and plants was minimized. The final total content of the main PAHs in the sorbent-amended soils did not exceed the maximal permissible levels that are accepted in most EU countries (1000–40,000 μg kg−1), and they did not accumulate in the aboveground phytomass of grasses in dangerous concentrations.

REPEATED WASTE OF HUMATIVES INTO PLAIN METALS IN THE PURIFICATION OF WEAKLY ACID WATER, TO CLEAN Cu2+, Pb2+

Destroyed military and industrial facilities have grave consequences not only for the country's economy, but also for the environment and natural resources. At present, humic acids are quite well known and have been sufficiently studied by the natural sorbent. Due to a wide range of functional groups, they perform accumulative, transport, regulatory, protective and physiological functions. The interaction of metal ions with humates does not have a single clear described mechanism. This is facilitated by the complexity and diversity of the structure of humic acids, as well as various reaction conditions in laboratory and natural conditions. Therefore, ways to increase the efficiency of sorption, improve and search for new properties of these substances still remain relevant.
 In this work, the possibilities of reverse bonding of copper and lead ions in slightly acidic aqueous solutions at pH values of 4,4–6,3 are shown. Humic acids were isolated from peat and brown coal, and potassium humates produced in China were also used. In this study, model solutions of copper (II) sulfate and lead (II) acetate were used with a calculated concentration in terms of copper and lead of about 400 and 1000 mg/dm3, respectively. The regeneration of metal humate complexes was carried out by lowering the pH of the medium to 2,1–2,2. The degree of lead sorption was 97–99 % for Pb2+ solutions with a concentration of 216 mg/dm3. Studies have shown the effectiveness of re-use of regenerated humates with a degree of metal release of 85–91 % in relation to the sorbed amount.
 The metal content in the experiment was determined by inductively coupled plasma atomic spectroscopy.
 It was also found that the ratio of the average values of the specific sorption of lead and copper was from 2,8 to 3,1 for various types of humic acids (humates). The proximity of these values with respect to the atomic masses of lead and copper (3,3), in the author's opinion, is associated with the interaction of copper and lead ions with humates in a stoichiometric ratio due to a chemical reaction (reactions). The sorption given in the experiment is described by a linear dependence in the coordinate system: the mass of the sorbed metal (ions) – the mass of humates.

Integrated Process of Ammonium Ion Adsorption by Natural Dispersed Sorbents

The process of adsorption treatment of effluents from ammonium ions is considered as an integrated two-stage process consisting of the stage of adsorption of contaminants by natural sorbents in the apparatus with a stirrer and the liquid separation stage and solid phases. Mathematical models of ammonium ions adsorption from effluents by natural dispersed sorbents are proposed, based on the assumption that the process is described by Langmuir and Friendlich isotherms. The values of ion exchange equilibrium constants for different types of natural sorbents have been established by identifying experimental data for theoretical dependences. The obtained constants can be used to calculate the average concentration of ammonium ions in the solution and in the grain of the sorbent in the process of integrated adsorption process. Based on the analysis of the research results, the optimum method of the spent sorbent separation was selected - separation of the suspension of purified ammonium-containing effluents - spent sorbent under the action of gravity. Indicators of optimization of complex process of sewage treatment from ammonium ions are offered.

Removal of Eosin dye from simulated media onto lemon peel-based low cost biosorbent

Synthetic dyes from different sources (wastewater and effluents) can be harmful to the environment even at minor quantity. Low cost natural biosorbent have been proved beneficial for water treatment and have excellent capability for the elimination of certain dyes from aqueous media. The present study purposed to utilize lemon peel as a natural sorbent for eosin dye in an aqueous media. The biosorbent were analyzed utilizing fourier transform infrared spectroscopy, scanning electron microscope (SEM), energy-dispersive X-ray analysis (EDX) and surface area analyzer (BET). The batch adsorption approach was carried out to optimize the basic parameters affecting the sorption phenomena. Anionic dye, eosin, was removed by adsorption utilizing lemon peel, as an biosorbent and such adsorption are affected by different physical factors i.e adsorbent dose, contact time, temperature etc. Freundlich and Langmuir's adsorption isotherm models are used to verify the results. The monolayer adsorption capacity was 8.240 mg/g at 30 °C that is calculated from Langmuir isotherm. The adsorption process is exothermic, shown by calculations thermodynamic parameters. Kinetics studies have represented that the adsorption process could be better explained by pseudo-second-order kinetics. All the parameters of biosorbent were compared with each other and proved that lemon peel, which is readily available, economic biosorbent, for the removal of eosin dye from the aqueous media.

Fatty Acid Composition of Muscle and Adipose Tissue in Pigs Fed with Addition of Natural Sorbents.

Simple SummaryDifferent types of unconventional feed resources as feed additives for animals are used worldwide on the basis of their availability and economical consideration. Natural mineral sorbents have been used in a wide range in animal farming mainly as feed additives since the mid-1960s. Still, to date, no studies have investigated the effect of the addition of natural sorbents such as biochar, bentonite–montmorillonite and zeolite–clinoptilolite to feed on the fatty acid content of pig meat (muscle tissue) and fat (adipose tissue). The presented research carried out in this area has revealed some evidence of fatty acid profile modification. In spite of the fact that effects of investigated sorbents were often opposite, they did not adversely affect indices of nutritional and pro-health quality of adipose tissue of the pig during fattening. Due to the fact that effects of sorbents supplementation are highly variable and can depend on the composition and dosage, further research seems fully reasonable.The fatty acid composition of meat and fat was studied in Choice Genetics line pigs fed a diet with three natural sorbents. Control (C1 and C2), biochar (D, 0.5%), bentonite–montmorillonite (A, 1.5%) and zeolite–clinoptilolite (B, 1.5%) diets were used in two trials. The samples of back fat, kidney fat and Longissimus lumborum (MLL) and Semimembranosus (MSM) muscle were examined. All sorbents (D, A and B) had no effect on fatty acid composition in MLL, whereas in MSM turned out to be very limited and inconsistent. Although A and B sorbents had a significant impact on the fatty acid profile of kidney fat, their effect was often opposite. Sorbent B’s effects were less beneficial due to a significantly higher proportion of saturated fatty acids, higher value of thrombogenic and atherogenic indexes, n-6/n-3 ratio but lower h/H ratio. Sorbent A’s effects significantly increased polyunsaturated fatty acids, and positively influenced lipid health quality indices. In summary, the feeding of natural sorbents slightly modified the fatty acid profile of muscle tissue, kidney fat and back fat; however, it did not have a negative effect on the indices of nutritional and pro-health quality of adipose tissue of pigs during fattening.

Electrospun polyacrylonitrile-Moringa Olifera based nanofibrous bio-sorbent for remediation of Congo red dye

The integration of polymers with biomaterials offers promising and effective nanomaterials with intrinsic and extrinsic properties that are utilized in several applications. The present work reported the development of Polyacrylonitrile (PAN) supported biosorbent (Moringa oleifera, (MO)) which was utilized for the removal of Congo red (CR) dye from aqueous solution. MO loaded polyacrylonitrile (PAN/MO) nanofibrous biosorbent was prepared by solvent homogenization method followed by electrospinning for the deposition of nanofibers. The developed nanofibrous biosorbent was investigated by several analytical techniques such as FESEM, TEM, XRD, FTIR, and XPS to study the material properties along with their control counterparts. The adsorption experiments such as the effect of contact time, effect of concentration, effect of pH, and reusability studies were performed. The adsorption capacity of the nanofibrous biosorbent is ∼52 mg g−1, which is significant as bulk sorbent when compared with other activated carbon in powder form. The adsorption capacities vary with an increase in the dye concentration and obtained ∼88% of dye removal. The adsorption data are validated using the empirical pseudo-first-order, pseudo-second-order kinetic models, and the mechanism involved in the adsorption phenomena was investigated by Langmuir and Freundlich isotherm models, respectively. The biosorbent follows the pseudo-second-order kinetics and Freundlich isotherm, which involves in multilayer adsorption phenomena. In a nutshell, the present work corroborated the importance of bio-based natural sorbent available in nature which can be effectively engineered with polymeric materials for obtaining novel hybrid materials to explore their inherent properties for various applications.

THE USE OF ALUMINOSILICATE CLAYS AS SORBENTS IN THE PURIFICATION OF MEDIA FROM HEAVY METAL IONS

Shown that galvanic production, which is engaged in the application of protective or decorative coatings on metal and non-metal products (galvanizing, nickel plating, oxidation), can also be attributed to enterprises that pollute the environment with wastewater. Subject to all the norms of the technological process, despite the various methods of surface treatment of products, a certain amount of wastewater of complex composition is still formed. With an inferior degree of purification, they are one of the sources of pollution of aquatic environments. The main toxic components polluting this kind of wastewater are heavy metal ions such as chromium-6, cadmium-2, lead-2 and other toxic substances. Shown that in wastewater treatment the main place belongs to the sorption method, which uses natural sorbents such as activated carbons, zeolites, bentonite clays, and other natural materials. Searched for natural raw materials to obtain effective sorbents during decontamination of industrial effluents. The chemical-mineralogical composition of a number of deposits of aluminosilicate rocks in Azerbaijan has been studied. An analysis of the results obtained made it possible to establish the optimal variant of the synthesis of sorbents. Based on a frame-type aluminosilicate zeolite (clinoptilolite) and layered aluminosilicate (bentonite) with a high content of montmorillonite, their Na-forms were obtained. The results of the physicochemical analysis of the natural material and its modified Na-form are presented. Sorption treatment of wastewater from some heavy metal ions on modified forms of bentonite and clinoptilolite was carried out. It has been established that, in terms of sorption properties, the obtained sorbents based on natural raw materials Na-clinoptilolite and Na-bentonite can be recommended instead of synthetic industrial KU-2-8 in the sorption extraction of heavy metal ions from wastewater

Use of Natural Sorbents in the Processes of Removing Biogenic Compounds from the Aquatic Environment

This paper presents the results of the evaluation of the possibility of using a selected sorbent of natural origin, mineral (opoka rock), for the removal of biogenic compounds from aqueous solutions. The analyzed opoka rock contains approximately 70% calcium carbonate (CaCO3) and from 26 to 27% silicon dioxide (SiO2) and has been classified as heavy opoka rock. The experiment focused on the sorption of organic components, including phosphorus (P), nitrogen (N) and carbon (C). It was carried out for two treatment systems, column tests and batch tests, for three samples of water—water from a water supply system, water from a fish pond and water from a garden pond—located in the region of Silesia (Poland). The results showed that the P removal efficiency was equal to 96.6% for the fine-grained sorbent (grain size <2 mm) and 90.8% for the coarse-grained sorbent (2–4 mm) in the batch tests, while lower effectiveness was observed for the column tests, reaching 67.8% and 54%, respectively. The efficiency of N (NH4+) removal was equal to 84% for both types of sorbents in the batch tests, while it was 47.7% for the fine-grained sorbent and 26.3% for the coarse-grained sorbent in the column tests. The efficiency of the removal of nitrate-nitrogen (NO3−) was higher for the fine-grained sorbent in all analyzed water samples. The use of materials of natural origin in industrial applications is a recommended direction, part of the green transition. The analyzed samples of opoka rock come from deposits, and opoka rock has so far not been analyzed in terms of its possible use in water and sewage treatment technology. Therefore, further research is recommended for this low-cost sorbent, which may be a competitive material for commercial products.

MODIFICATION OF NATURAL OIL SORBENT FOR IMPROVEMENT OF HYDROPHOBICITY

A sorbent made of natural materials (moss) was selected for the sorption of diesel from the surface of the water. The sorbent was modified to increase its hydrophobic–oleophilic characteristics. Typical natural organic sorbent from moss was selected and modified in three different ways: processed with hot water (80 °C and 100 °C), mercerized and coated with oil–water (10% and 50%). Water, diesel sorption capacity, and oil retention tests were performed. Tests showed that simple treatment with hot water and alkali can change surface properties and improve sorption capacity. Modification with hot water at 80 °C enhanced sorbents’ oil sorption capacity and showed the best results but meanwhile, this method readily increased hydrophilicity. This method of sorbent treatment could not be applied in cases where sorbents are used to clean oil spills from water surfaces. Meanwhile, better sorption results would be obtained in cases where cleaning operations take place on soil and other solid surfaces.

Removal of Petroleum Hydrocarbons from Brackish Water by Natural and Modified Sorbents

Crude oil and petroleum products made from it are increasingly being extracted and consumed worldwide as an important energy source. During necessary transportation, e.g., by tanker, an oil spill might occur, which leads to water pollution by oil. One of the methods of cleaning up oil spills is to use sorbents, preferably made from natural materials. This study evaluates the remediation efficiency of brackish water polluted with crude oil, marine diesel oil (MDO) and lubricating oil. The experiment was performed with three different sorbents (straw, straw modified with methoxytrimethylsilanes (MTMS) and wood chip shavings) and without them. The evaporation loss and the dissolved and sorbed fractions of oil were measured by gas chromatography (GC) to evaluate remediation efficiency. Hydrophobization made the natural sorbents buoyant for the duration of the experiment, with only a slight increase in the maximum sorption capacity. The sorbents increased the evaporation of the oils and also of the water, reduced the proportion of the oil dissolved in water and retained the sorbed proportion for the lubricating oil and partly for the MDO, to such an extent that it could not be extracted entirely even after a 60-min extraction time.

Environmental Performance and Operational Analysis of a Sewage Sludge Fermentation Solid Oxidation Fuel Cell System Using Fe<sub>2</sub>O<sub>3</sub> and Kanuma Clay

This study discussed the performance of an integrated indirect gasification solid oxidation fuel cell (IIG-SOFC) in consideration of LCA thinking. Generally, hydrogen sulfide (H2S) in gasified biomass causes cell voltage in a stack to decline over time. Although the biomass resource such as sewage sludge are carbon-neutral, a decline in SOFC performance creates environmental disadvantage of global warming potential (GWP); as such, it is necessary to remove H2S via adsorption, and typically, ferric oxide (Fe2O3) is used for desulfurization. However, Fe2O3 imposes a considerable environmental burden of abiotic depletion potential (ADP). Kanuma clay (Kc) which is a natural sorbent was proposed as a viable substitute in our previous study, but Kc is characterized by a low adsorption capacity. As such, limitations associated with the adsorption column size and frequency with which adsorbents should be changed mean that utilizing a large amount of Kc does not necessarily result in a high desulfurization rate. Therefore, we investigated the optimal performance of IIG-SOFC utilizing Kc using exergy analysis and LCA. As a result, the maximum exergy efficiency was 28.2%. Likewise, the smallest GWP and ADP was achieved at a desulfurization rate of 100%, Kc usage ratio of 4.5%, and adsorption temperature of 120 °C.

Mosses as a biomonitor to identify elements released into the air as a result of car workshop activities

Human activity as a result of civilization development contributes to creating new sources of environmental pollution. Air pollution is one of the major problems because it affects the fauna and flora, and people themselves. There is a lack of public awareness of the level of atmospheric analytes pollution emitted from people's occupational and recreational (leisure) activities. A quick, cheap and easy way to investigate the state of the environment is to use organisms-biomonitors that indicate the level of environmental pollution. The study aimed to assess air pollution in an urban area using three moss species: Sphagnum fallax, Pleurozium schreberi and Dicranum polysetum. Mosses were exposed for 90 days, and the effects of traffic and car workshop activity on the increments in elemental concentrations were assessed using instrumental neutron activation analysis (INAA) and flame atomic absorption spectrometry (F-AAS). The actual quantum yield of Photo System II (PSII) photochemical was also analyzed to assess changes in moss vitality during the experiment. The results showed that the concentrations of individual elements in mosses and thus in the atmospheric aerosol depend on the site of exposure. The difference in analyte concentrations between outdoor and indoor environments depends on the type of element and its source. The mosses exposed in the workshop were good bioaccumulators of elements such as Al, Cr, Fe and Ba, whose concentrations were higher inside than outside and their emission sources related to the activities of the car workshop were defined. The mosses remained vital in the air during the exposure period, while they worked as a natural sorbent inside the workshop.

Sorption and Mobility of Charged Organic Compounds: How to Confront and Overcome Limitations in Their Assessment.

Permanently charged and ionizable organic compounds (IOC) are a large and diverse group of compounds belonging to many contaminant classes, including pharmaceuticals, pesticides, industrial chemicals, and natural toxins. Sorption and mobility of IOCs are distinctively different from those of neutral compounds. Due to electrostatic interactions with natural sorbents, existing concepts for describing neutral organic contaminant sorption, and by extension mobility, are inadequate for IOC. Predictive models developed for neutral compounds are based on octanol–water partitioning of compounds (Kow) and organic-carbon content of soil/sediment, which is used to normalize sorption measurements (KOC). We revisit those concepts and their translation to IOC (Dow and DOC) and discuss compound and soil properties determining sorption of IOC under water saturated conditions. Highlighting possible complementary and/or alternative approaches to better assess IOC mobility, we discuss implications on their regulation and risk assessment. The development of better models for IOC mobility needs consistent and reliable sorption measurements at well-defined chemical conditions in natural porewater, better IOC-, as well as sorbent characterization. Such models should be complemented by monitoring data from the natural environment. The state of knowledge presented here may guide urgently needed future investigations in this field for researchers, engineers, and regulators.

Агроинженерная технология улучшения качества дренажно-сбросных вод с рисовых оросительных систем

Under condition of water shortage slow-mineralized drainage water coming from the rice irrigation systems can be used as an additional source of water. Agro-engineering technology on drain-age flow treatment and its reusing for irrigation has been devel-oped and tested by the authors. Agro-engineering technology in-cludes: 
 1) biosorption facility to remove mineralsalts with the help of specially selected natural mineral sorbents, 
 2) higher aquatic vegetation to absorb biogenic substances; 
 3) the developed new sorbent to provide water conditioning. The results of biosorption facility testing carried out at the Sarpin irrigation system in the Republic of Kalmykia showed its high ef-ficiency.
 A decrease in drainage flow mineralization was observed (from 4.3 to 0.66 g/l), while chlorine decreased from 78 to 28 mg/l, as well as calcium increased from 100 to 124 mg/l. So the efficiency of the suggested technique of drainage flow treatment is rather high which made it possible to use purified drainage flow for irrigation purposes without negative consequences. The appli-cation of the developed technology will get an economic effect by reducing the cost of water supply for the rice irrigation system.

Assessment of the influence of the composition of the soil-sludge mixture for the reclamation of disturbed lands on the content of oil products and heavy metals

The article considers a method for the disposal of drill cuttings for the reclamation of disturbed lands. The soil and sludge mixture for restoring disturbed lands is oil production waste, sand and peat mixed in a given ratio; if necessary, sorbents and oil flora destructors can be added. The authors conducted an information search for raw materials that are used for the industrial production of oil sorbents on the Russian market. Vermiculite used in this work is a natural sorbent and biostimulant. In order to evaluate the contribution of each of the added components to the properties of the resulting soil-slurry mixture and to select their optimal ratio, an experiment planning matrix was compiled. The authors have shown that in terms of physical and chemical properties, soil-slurry mixtures with different content of components meet the requirements for reclaimed lands. Unremediated drill cuttings, when sludge pits are overfilled or destroyed, or simply improperly stored without arrangement, lead to an increase in environmental pollution with oil and oil products, heavy metals and other chemicals. As a result of the research, regression equations were obtained for the sorption of oil products and lead ions depending on the content of peat, sand and vermiculite. It was shown that the content of sand in the soil-slurry mixture has the greatest effect on the absorption of oil products, while a change in the amount of peat and vermiculite has little effect on the content of oil products in the soil. The content of lead ions is most affected by the amount of vermiculite introduced; peat also showed good sorption capacity for lead in the composition.